Symmetry-enabled discovery of quantum defects in two-dimensional materials

Point defects in solid-state materials such as NV center in diamond have been demonstrated to be promising qubit candidates for quantum information science and technologies. Being atomically thin, two-dimensional (2D) materials renders a new paradigm for the realization of quantum defect fabrication and controllable manipulation. In these 2D materials, searching for defects with triplet ground states is one of the most crucial steps to identify more NV-like quantum defects that support multiple quantum functionalities. We design a comprehensive workflow for identifying promising quantum defects in a large group of 2D materials based on a site-symmetry-based hypothesis, which significantly increases the probability of finding triplet spin defects. To identify multiple functionalities for these quantum defect candidates, their magneto-optical properties are comprehensively estimated from high-throughput computations. We demonstrate that antisite defects in various hosts, including post-transition metal monochalcogenides (PTMCs) and transition metal dichalcogenides (TMDs) are promising quantum defects. Most importantly, we propose that 16 antisites in PTMCs serve as the most promising 2D-material-based quantum defect platform, due to their well-defined defect levels, optimal magneto-optical properties, and the availability of host materials.